The present invention relates to electronic test instrumentation, and in particular, to a Vector Network Power Meter (VNPM) as a new class of electronic test instrument that combines the functionality of a Power Meter with that of a Vector Network Analyzer (VNA) and is particularly useful for Radio Frequency (RF) test applications. The present invention further relates to frequency conversion architecture, and in particular, to frequency conversion architecture provided for wide frequency range signal correlation networks.
A Power Meter operates as a signal receiver and performs power level measurements with Power Meter instrument(s) attached to one or more output ports of the device under test (DUT). A conventional Power meter introduces measurement inaccuracy due to the mismatch or reflection of signals at the connection between the DUT and the Power Meter. Also, a conventional Power Meter acts as the endpoint or load for the measured signal and consequently does not allow simultaneous or parallel measurements upon a DUT output signal.
A VNA operates as a signal source and signal receiver to perform magnitude and phase measurements of transmission or reflection, also called scattering parameters (S-parameters). Measurements of S-parameters are currently performed with a VNA instrument attached to one or more input or output ports of the DUT. Existing VNAs calculate S-parameters in a controlled test setup where the VNA is calibrated and connected to the DUT with external cabling. The effects of that external cabling must be calibrated out as a separate step. Drift phenomenon such as temperature-related changes in the electrical length of the cabling can affect the VNA measurement accuracy. Also, the VNA performs S-parameter measurements in a controlled test setup that does not allow other simultaneous measurements upon the DUT signals.
Additionally, correlator networks are used in microwave signal processing to measure the relative amplitude, relative phase, or complex ratio of two signals. In particular, a six-port, or n-port, reflectometer incorporates such a correlator as part of its signal processing. A common implementation of a correlator network utilizes tuned microwave elements, such as quadrature couplers, to perform the necessary signal processing at the fundamental microwave measurement frequency. These tuned microwave elements are inherently limited in frequency range, and are commensurate in size with the wavelengths of the microwave signals being processed.